In recent years, digital transmitters in which ΔΣ modulators and class D amplifiers are combined have attracted attention as transmitters for which high power efficiency is expected. The ΔΣ modulators using ΔΣ modulation schemes have actively been studied because hardware implementation is easy.
Patent Document 1 and Non Patent Document 1 disclose technologies for ΔΣ modulators using low-pass ΔΣ modulation schemes as related technologies.
Patent Document 2 discloses a technology for a ΔΣ modulator using an envelope ΔΣ modulation scheme as a related technology.
Non-Patent Document 2 discloses a technology for a ΔΣ modulator using a band-pass ΔΣ modulation scheme as a related technology.